Messages in this thread | | | Date | Fri, 25 Aug 2006 15:48:56 +0200 | From | Arjan van de Ven <> | Subject | Re: [RFC] maximum latency tracking infrastructure (version 2) |
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Jan Kiszka wrote: >> The patch below adds infrastructure to track "maximum allowable >> latency" for >> power saving policies. > > Very interesting approach. I wonder if it could be used to cover > another problematic source of latencies as well: asynchronous SMIs. > They quickly cause delays reaching from a few 100 us up to > milliseconds. > > Hard-RT extension like Xenomai work around this on several Intel > chipsets by disabling SMI unconditionally
I would consider that a mistake. SMI's are used to do things like emergency thermal protections etc etc. Disabling them unconditionally is going to risk you your hardware.
> I guess an interface to let also applications / the sysadmin specifiy > a latency constraint would be useful as well. sysfs?
I thought about this a lot but decided against. There are already ways to do things like disable specific C states etc, and if we expose this it'll mostly get abused by certain desktop applications who have no idea what they are doing ;=( What makes anyone think that userspace could make a better decision than the drivers? Video / Audio playback are not good examples since these both already would work automatically correct with only in-kernel infrastructure. Hard-RT systems are also not a good example since those should use the existing boot parameters. I couldn't come up with other scenarios, and until we have a good one I'm against exposing crap to sysfs "just because we can". - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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